Fluoropolymer compositions are known having utility as textile treating agents. These fluoropolymers generally contain pendent perfluoroalkyl groups of three or more carbon atoms, which provide oil- and water-repellency when the compositions are applied to fabric surfaces. The perfluoroalkyl groups are generally attached by various connecting groups to polymeric groups not containing fluorine which form the backbone polymer chains of the resulting copolymer. These backbone polymers may be (meth)acrylates, vinyl, vinylidene or other groups. They may act to extend the performance of the more expensive perfluoroalkyl groups, act as bonding agents to fix the copolymer to the fabric, or may serve other functions.
Generally, such copolymers are prepared in an aqueous emulsion stabilized with a cationic, nonionic or anionic surfactant. While it is not unusual for a nonionic surfactant to be used in combination with a cationic or anionic surfactant, a cationic and anionic surfactant are not combined as emulsion stabilizers because of their potential reactions with each other. However, some uses of combined cationic and anionic surfactants have been disclosed to obtain certain end-product characteristics in cosmetic, photographic and other non-textile applications.
While fluoropolymer-(meth)acrylate compositions disclosed in the prior art may be satisfactory under certain application conditions, their aqueous emulsions are not sufficiently stable under some harsh conditions. For example, under a highly anionic and/or high alkalinity environment, such as produced by the strong alkali remaining on a fabric after mercerization, the emulsion from prior art compositions will turn dark and precipitate within a few hours. In other applications, where the fluoropolymer emulsion is subjected to high shear conditions or high temperatures, the emulsion may also destabilize, resulting in precipitation of the polymer from the dispersion. Such failures can be extremely costly. Compositions and processes for preparing fabric treatment agents having improved stability under these conditions are of significant interest to the textile and apparel industries. The present invention provides such compositions and processes.